Fluid bed polymerization catalyst injection system

ABSTRACT

Polymerization catalysts in the form of dry powders are continuously fed to a fluidized bed reactor under essentially plug-flow conditions by a sequential repetition of the steps of dispensing under controlled conditions, a desired quantity of catalyst from a catalyst supply source to a chamber which is alternately communicable with such supply source and the reaction zone of the fluidized bed reactor, isolating the dispensed catalyst from the catalyst supply source, exposing the dispensed catalyst to the reaction zone of the fluidized bed reactor and rapidly injecting the catalyst into the reaction zone with a carrier gas.

United States" Patent 1191 Miller 1111 3,790,036 Feb. 5, 1974 FLUID BEDPOLYMERIZATION CATALYST INJECTION SYSTEM Inventor: Adam Roy Miller,South Charleston,

W. Va.

Assignee: Union Carbide Corporation, New

York, NY.

Filed: Nov. 21, 1969 Appl. No.: 878,774

US. Cl. 222/194, 302/49 Int. Cl. B6Sg 69/06 Field of Search..... 222/1,53, 61, 70, 193, 194,

References Cited UNITED STATES PATENTS 3/1939 Hagenm, 222/194 10/1953Smith 222/194 X 6/1966 Evenson et a1. 222/195 X 2,914,223 11/1959Richter 222/194 Primary Examiner-Stanley H. Tollberg AssistantExaminer-Larry Martin Attorney, Agent, or Firm -James .1. OConnellsupply source to a chamber which is alternately communicable with suchsupply source and the reaction zone of the fluidized bed reactor,isolating the dispensed catalyst from the catalyst supply source,exposing the dispensed catalyst to the reaction zone of the fluidizedbed reactor and rapidly injecting the catalyst into the reaction zonewith a carrier gas.

4 Claims, 3 Drawing Figures From Catalyst 20 Preperalion Unir ADJUSTABLETIMER CA1v1 ITIMER 32 Carrier I Gas w 10 v '42 97 K Fluid v ,7 Bed jg.36' Reactor Gas Feed PATENTEUFEB 51914 3.790.036

sum 1 0F 2 Gas Recycle Cafalysr Feed Gas Feed INVENTOR ADAM R. MILLERQZZQQQ PATENTED 5 9 sum 2 From Cafalysr Preperarion U it 32 Carrier 4Gas v I 36 I Gas I z? Feed From Caralysr' 0 Preperafion Unir 25,2Carrier a Gas I w v v J6 Gas Feed 4W ADJUSTABLE TIMER CAM TIMER FluidBed Reactor CAM TIMER Fluid Bed Reacior INVENTOR ADAM -R. MILLER eafigegFLUID BED POLYMERIZATION CATALYST INJECTION SYSTEM BACKGROUND OF THEINVENTION Considerable attention has recently been focused on thefluidized bed reactor as a tool for the polymerization of gaseousmonomers to solid particulate polymers, particularly olefin polymers,with solid powdery catalysts. Fluidized bed reactors for the productionof particulate polymers may be generalized as operating by continuouslyfeeding a dry powdery catalyst and a gaseous stream containing thepolymerizable monomer to a fluidized bed of formed and forming polymerparticles, while removing heat and aportion of the bed as the product.The only raw materials required are the polymerizable monomers, catalystand any modifying or diluting gases. As no solvents are employed in thesystem, the fluidized bed reactor represents a promising tool forlowering polymer production costs.

To avoid subsequent catalyst recovery steps requires the use of highlyactive catalysts such as, in the instance of polyolefin production, thesilylchromate catalysts disclosed in US. Pat. No. 3,324,101 tovBaker andCarrick and US. Pat. No. 3,324,095 to Carrick, Karapinka, and Turbettwhich are hereby incorporated by reference. In addition to being highlyactive, these catalysts when supported on a porous support, show anability to subdivide to produce a multitude of polymer particles from asingle catalyst particle. Polymer particles so produced are so low incatalyst residue that they I can be used directly without catalystrecovery. 7

When using a highly active catalyst, a problem exists in feeding aconcentratedmass of catalyst to a reactor. There is a tendency for alocalized run-away reaction in or about the catalyst feed system tooccur due to initiation of polymerization with a concentrated mass ofcatalyst particles. This results in plugging of the feed system. A needtherefore exists for a system to feed catalysts to a fluid bed reactorcontinuously, without recurrent shutdowns due to plugging as caused byadverse polymerization phenomena.

SUMMARY OF THE INVENTION It has now' been found that dry powderypolymerization catalysts can be effectively and continuously fed to afluid bed reactoi under essentially plug-flow conditions by a sequentialrepetition of the steps of dispensing under controlled atmosphereconditions, a desired quantity of catalyst froma catalyst supply sourceto a chamber which is altemately communicable with the catalyst supplysource and reaction zone of a fluidized bed reactor, isolating thedispensed catalyst from the catalyst supply source, exposing thedispensed catalyst to the reaction zone of a fluidized bed reactor andrapidly injecting the catalyst into the fluid bed reactor with a carriergas. In this manner catalyst concentration in the reaction zone can beeffectively controlled by varying the amount of catalyst dispensed fromthe catalyst supply source during each cycle or by varying the timeintervals between injections of predetermined quantities of catalystinto the reactor. As will be appreciated, the process of this inventionmakes possible the supply of finely 'divided catalyst in a form andunder conditions which approach those-of plug-flow for cohesive masses.In effect then, when considering the finely divided state of thecatalyst and the dispersing effect due to the velocity of the carriergas, the catalyst can be said to be supplied in more or less discreteunits somewhat comparable to that of ideal plug-flow.

According to this invention there is also provided an apparatus for theplug-flow or discrete unit feeding of catalyst into a fluidized bedreactor.

DRAWINGS DESCRIPTION In one embodiment of this invention there isprovided a method for feeding catalysts under'plug-flow conditions intoa fluidized bed reactor by dispensing small units of catalyst particleswhich are sequentially injected into the reactor by a carrier gasstream. The catalyst prior to injection is stored in some reservoirnormally under an inert gas to protect it from poisons prior to use.

The operation of the catalyst feed system of this invention can bebetter understood by an explanation of its role in the total operationof a fluid bed reactor. With reference now to FIG. 1, the fluid bedreaction system comprises a reactor 10, which generally consists of areaction zone 12 and a velocity reduction zone 14.

The. reaction zone 12 comprises a bed of growing polymer particles,formed polymer particles and catalyst.

tain a viable fluidized bed,mass gas flow is typically in v the order offrom 2 to about 6 G or more,'with fluidization achieved by a high rateof gas recycle to and through the bed typically in the order of about 50times the rate of feed or makeup gas. G is used in the accepted form asthe abbreviation for the minimum mass gas flow required to achievefluidization, C.Y. Wen and Y.I-I. Yu, Mechanics of Fluidization,Chemical Engineering Progress Symposium Series, Vol. 62, pages lOO-l 10(1966). In general, the fluidized bed appears as a dense mass of viableparticles in possible free vortex or bubbling flow as created by theperculation of gas through the bed with free vortex or bubbling flowestablished by the fact that axial pressure drop through the bedgenerally is only in the order of about 1 psig.

In the normal or continuous operation of the fluid- .ized bed,makeup'gas is fed to the bed at a rate about equal to the rate at whicha portion of the bed is withdrawn as product. That portion of thegaseous stream which does not react in the bed constitutes recycle gaswhich is removed from a polymerization zone preferably by passing itinto a velocity reduction zone 14 wherein retained particles or finesare given an opportunity to return to the bed. Return may be furtheraided by a cyclone 16 which may be part of the velocity reduction zoneor exterior thereto. The recycle gas is. then typically passed through afilter 18 to remove more fine particles, through a heat exchanger 20 andcompressor 22 where it is stripped of heat of reaction before it isreturned to the bed at point 24 below a distributor plate 26 whichserves to diffuse the gas through the bed to keep the particles at thebase of the bed viable and to support a quiescent bed ofresin particleswhen the reactor is not in operation.

The most unique feature of a fluidized reactor bed system for theproduction of solid particulate polymers is that, with the possibleexception of start up, the bed is the product. Accordingly, as new bedis created through polymerization, an equal portion is withdrawn asproduct preferably at about the base of the bed 28.

When used for polymerization of olefms, hydrogen is typically a normalcomponent of the gaseous stream to modify melt index of polymersproduced in the bed. Other gases, such as nitrogen and like may also bepresent as diluents.

Fluidized bed reactors normally operate at pressures from about 40 to300 psi or more and at temperatures ranging from the minimumpolymerization temperatures for polymers to be prepared therein up tosome temperature below the sintering point of the polymers beingproduced. In the polymerization of olefins this upper temperature isabout 100C.

Dry powdery catalysts used for the polymerization of polymers in afluidized bed reactor are normally injected into the bed at a point 30which is preferably above distribution plate 26 and more preferably fromabout one-fourth to three-fourths of the height of the bed.

In a typical systemcatalyst concentration in the bed will range fromabout 0.001 to about 0.50 per cent of bed volume depending onproductivity desired. While catalyst concentration in the bed is small,catalyst concentration in the feed system is extremely high, and it hasbeen difficult to maintain continual feed for long periods of time dueto plugging of the feed system as mainly caused by reactions initiatingin or about the catalyst feed system.

It has been found that catalyst concentrations in a fluidized bedreactor can be maintained within desired levels when fed under timedplug or unit flow conditions. Using plug-flow feed and suitableapparatus, it has further been found that plugging can be substantiallyeliminated without interfering with substantially steady stateoperation'of the reactor. j

The schematic diagram of FIG. 2 may be used to illustrate and explainthe method and associated apparatus for feeding catalyst to a fluidizedbed reactor under conditions of this invention. Apparatus asschematically illustrated in FIG. 2 is normally placed in closeproximity to the fluid bed reactor and generally includes catalystreservoir 32 which supplies catalyst for injection to the reactorthrough sequential operation of metering valve 34 and valve 36, thecatalyst entering the reactor through inlet tube 38.

More specifically, the drypowdery catalyst is fed from a preparationunit, not shown, to the catalyst reservoir 32 where it is kept under aninert atmosphere conveniently supplied through catalyst feed line 40.Reservoir 32 is connected to a chambered metering valve 34, whose portor chamber 42 can be pneumatically, electrically or otherwise actuatedto be in line as shown, with the outlet of reservoir 32 or in line withinlet tube 38, typically its normal position.

When a charge of catalyst is called for, the chamber 42 of the meteringvalve 34 is turned to face the outlet of the catalyst reservoir 32anddry powdery catalyst is allowed to fill the chamber. Chamber 42 isthen turned to face inlet tube 38. Valve 36 is opened and'a surge ofcarrier gas, which may be the reactive monomer, a modifying gas, inertgas, mixtures thereof and the like from gas reservoir tank 44, isallowed to blow catalyst particles from chamber 42 of metering valve 34through valve 36 and inlet tube 38 into the reactor before a deleteriousreaction can possibly begin in a zone between valve 34 and inlet tube38. An orifice valve 46 may be conveniently placed ahead of gasreservoir 44 so that a controlled volume of gas will be accumulated at apressure greater than the reaction pressure, preferably from about 1.1or 1.2 to about 1.5 or 2 times reactor-pressure, and to prevent acontinued flow of gas through metering valve 34 between injections. Theoperation of metering valve 34 and valve 36 may be convenientlycontrolled by a cam timer 50 whose sequence of operation is in turncontrolled by an adjustable timer 48 which actuates the cam timer andmay be set to control the time intervals between catalyst injection. Toassure there is no back pressure or flow of polymer particles orcatalyst backwards into the catalyst feed system there is preferablysupplied a continuous positive flow of gas at point 51 ahead of valve 36through inlet tube 38.

An important function of catalyst feed system of this invention is toprovide a controlled interface between the carrier gas and the catalyst,particularly when the carrier gas is reactive with the catalyst. Whenthe carrier gas is reactive no lasting interface can be tolerated. It isimportant, in this instance, to have the carrier gas sweep through thefeed system at a velocity sufficient to substantially instantly carryall catalyst particles into the reactor. It has been found that with acarrier gas velocity from about 60 to about feet per second each unitcharge of catalyst will be effectively carried into the reactor withoutleaving a residue of catalyst particles in the feed monomer for possiblereaction. Lower velocities may be advantageously employed where thecarrier gas is inert, however, this could lead to a possibleaccumulation of particles along the feed system surfaces and theirpresence could lead to plugging because of catalyst particles stickingwhen the carrier gas is switched to be of a reactive nature. In additionto controlling the charge of catalyst which may be fed to the reactorduring any one sequence, the metering valve 34 must play the additionalfunction of sealing catalyst reservoir outlet from the carrier gas.Accordingly, valve tolerances must be close since leakage of reactivecarrier gas back into the catalyst storage system cannot be tolerated aseven a small amount will polymerize and lead to plugging of feed linesor jamming of the valve.

As indicated it is important during any one injection cycle to sweep outof the feed system and into the reactor all catalyst particles so as toprevent a deposition which could lead to a cumulative growth of polymerlayers and eventually plug the monomer feed. While aided by the supplyof a carrier gas of a sufficiently high velocity, providing all thetubes and valves which comprise the feed system with highly polishedsurfaces will minimize the deposition of catalyst particles andsubsequent formation of polymer layers.

It is contemplated that catalyst systems using silica bases as thesupport will be used. In this connection supports of a size from aboutan average of mesh to preferably about 250 mesh are preferred with thelarge mesh supports having a reduced tendency to ac- 'pable of removing.

cumulate in the feed system. With particles of such size, it has beenfound that the ordinary density of the particles in the catalystreservoir ranges from about to about 25 pounds per cubic foot at rest.When metered into the metering valve 34 and exposed to carrier gashaving a velocity of from about 60 to about 90 feet per second, it isestimated that the bulk density of the particles may be reduced by about50 percent without adverse effects.

Time intervals between injections and the volume of injected catalystparticles depend on many factors including productivity of the catalystand the nature of the carrier gas. It has been found that depending onproductivity (unit weight of polymer per unit weight of catalyst perhour), catalyst injections can be varied from one per minute or less toas few as about 1 per 120 minutes or more without materially upsettingthe steady state operation of the reactor.-This variation is madepossible inasmuch as the fluidized bed appears to have a great toleranceto self average its inputs and signiflcant changes in input of catalystparticles have been observed to berequired to upset an essentiallysteadystate operation.

As indicated, the fluidized bed reactor appears to be quite flexible inthe amount of catalyst it can accept in each injection withoutdisplaying an adverse reaction. It is considered that the major limit isthat amount which would at least initially increase the heat of reactionbeyond that which the heat exchange system is ca- The nature of thecarrier gas is of consideration to any determination of the rate ofcatalyst injection, assuming the quantity is not destined to overloadthe system. The ideal rate of injection is equal to the rate of catalystconsumption. It is usually only feasible to operate close to thisrate'where the carrier gas is inert or substantially inert to thecatalyst. This can be achieved where the carrier gas must be inert gas,because the monomer is too active to be brought into contact with anyconcentrated amount of catalyst particles. When for use as the carriergas. This is most feasible when the amount of modifying gas required ina particular reaction is sufficiently high to permit its use as theexclusive carrier gas without fear of build-up of excess quantities.Where lower amounts of modifying gas are to be present in the reactorsystem a modifying gas may be used but venting may also be required fromtime to time.

Catalyst may also be injected at a rate substantially equal to itsconsumption. through use of comonomer. Comonomers normally are lessreactive than the major monomer content of a gas feed stream. Whererequired in adequate amounts, comonomers too can be diverted from themain gas feed stream for use as the carrier gas in the same manner asmodifying gas.

Where it is necessary to use monomer as all or part of the. carrier gasas in the instance of homopolymerization in the absence of modifyinggases, it is preferred to maximize time intervals, in the mannerpreviously indicated, between catalyst injections. It is estimated thatmore than 99 percent of all particles are carried into the reactor witheach charge of carrier gas. Between injection intervals the continualgas fed at point 51 acts to sweep the remaining particles into thereactor.

Proper adjustment of the pressures of blanketing gas in catalystreservoir 32 and gas reservoir 44 also assures more satisfactoryoperation. The pressure of the blanketing gas applied to catalystreservoir 32 should be equal or exceed the pressure applied to gasreservoir 44 and exceed the pressure within the reactor to prevent thepossibility of any back up of catalyst particles and reactive monomerinto the feed system. The pressure reached in gas reservoir 44 shouldalso be preferably greater than reaction pressure to assure that flowwill always be positioned in the reactor direction. In addition, thepressure of that portion of monomer fed at point 51 should exceedreactor pressure.

Consideration must also be given to the sequence of injections as afunction of catalyst productivity. A sequence can be set manually orautomatically on a schedule preferably based on temperature differencesbetween input and recycle gases. The greater the temperature differencethe more vigorous the reaction. Since the object is to maintain normallya substantially steady state operation, a constant temperaturedifference is preferred. Catalyst injection may be increased ordecreased stepwise by trial anderror to achieve steady state operation.This adjustment of rate of injection may be achieved automatically, forinstance, by detecting temperature differences with thermocouples whoseoutputs are converted by a transducer to a pneumatic signal which is inturn fed to a servo valve which adjusts the operation of timer 48 whichin turn controls cam timer 50 to seek and eventually adjust to thetemperature differential sought. Without being limited, as analternative, it is within the ambit of this invention to employ a devicelike a computer to calculate the amount of heat generated in the reactorand use this information to continually adjust a timer mechanism toachieve a rate which will hold heatof reaction at a constant level.

Without being limited, there is included within the scope of thisinvention the apparatus of the schematic illustration shown in FIG. 3which is also utile in achieving trouble-free injectionof catalyst intothe re actor. Again catalyst is contained in reservoir 32 under ablanket of inert gas supplied to line 40. When a charge of catalystiscalled for, a mechanism controlled by a suitable means such' asadjustable timer 48 and cam timer 50 opens valve 52 while maintainingvalve 54 in a closed condition to allow catalyst to meter into the zonebetween valves 52 and 54. Valve 52 then closes, valve 54 opens, allowsthe carrier gas to shove the particles of catalyst over into venturivalve 56. The flow of feed gas there blows the catalyst charge into thereaction zone of the fluidized bed through tube 38 mounted on a wall ofthe reactor 10. All of the operating criteria and considerationnecessary to the utility of the system shown in FIG. 2 apply to thesystem shown in FIG. 3 with one additional requirement, that being topreferably provide a check valve 58 which precludes gas pressure in thefeed falling below reactor pressure or below carrier gas pressure.

EXAMPLE I An ethylene polymerization catalyst was prepared by firstdepositing bis-triphenyl silyl chromate on a silicon support of thefollowing composition:

and having the following physical characteristics:

Mesh Size, US. Standard Weight Per Cent Larger Than 60 0.0 max. 100 4.0max. 140 10.0 max. 200 9-33 Surface Area 338 sq. meter per grain PoreDiameter (average) 170 Angstroms The deposited bis-triphenyl silylchromate was then reduced with ethoxydiethyl aluminum in a ratio ofabout 12 moles of ethoxydiethyl aluminum per mole of bis-triphenyl silylchromate to provide the desired catalyst.

To the fluidized bed reactor system shown in FIG. 1 having a reactordiameter of 8 feet and capable of operating with a nominal bed depth ofpolyethylene particles of about 20 feet there was attached a catalystfeed system of the type depicted in FIG. 2. The polymerization catalystis stored in the reservoir under a nitrogen blanket and fed to thereactor using nitrogen as the carvrier gas. Ethylene'was polymerized inthe presence of one per cent by weight of hydrogen and 3 percent byweight of butene at a reaction temperature of 90C. and a reactorpressure of 260 psig. Under these conditions the carrier gas pressureand the inlet tube sweep gas pressure were maintained at 320 psig so astoprovide a carrier gas velocity in the inlet tube of from 60 to 90 feetper second during catalyst injection. Injection of the catalystparticles occured in units at intervals of one injection per hour up toone injection per 2 hours, depending upon the reaction temperature, andin a volume to provide a catalyst concentration in the reaction zone offrom 0.05 to 0.1 percent of the bed volume. Over the period of catalystinjection by the process described, continuous particulate polyethyleneproduction at the rate of 3,000 pounds of polyethylene per pound ofcatalyst .was obtained without disruption in catalyst feed (due toplugging) or steady state operation.

EXAMPLE 11 Using the fluidized bed reactor system and the catalyst feedsystem employed in Example I, a bis-triphenyl silyl chromate depositedon a silica support having an average diameter of about 100 microns andactivated with 12 moles of ethoxydiethyl aluminum per mole of silylchromate was fed with a nitrogen carrier gas in units of 0.6 pounds atintervals of from 30 to 60 minutes to the reactor. Under ethylenepolymerization conditions, in the presence of 1 percent by weight ofhydrogen and a minor amount of butene, of 90C. reactor temperature and100 psig reactor pressure, the carrier gas pressure and the inlet tubesweep gas pressure were set and maintained at 130 psig to provide acarrier gas velocity varying from 60 to 90 feet per second. The catalystconcentration was maintained at from 0.05 to 0.10 per cent of bed volumeduring the reaction period and from 1,000 to 2,000 pounds of particulatepolyethylene per pound of catalyst was produced during the reactionperiod without disruption in catalyst feed or steady state operation.

EXAMPLE III Following the procedure of Example I, ethylene waspolymerized in the presence of 4.8 percent by weight of hydrogen at areaction temperature of 97C. and a reactor pressure of 260 psig using acatalyst of bicyclopentadienyl chromium deposited on a silica supporthaving an average diameter of about 100 microns. The catalyst was fedfrom the feed system shown in FIG. 2 with the aid of nitrogen as thecarrier gas at an injection rate of one every 60 to minutes and at aunit volume so as to maintain catalyst concentrations of from 0.033 to0.067 per cent of bed volume. The carrier gas pressure and the inlettubesweep gas pressure were maintained at 320 psig and the velocity ofthe carrier gas during injection was in the range of from 60 to feet persecond. From L500 to 3,000 pounds of particulate polyethylene per poundof catalyst was produced over the reaction period without disruption ofthe polymerization process.

What is claimed is:

l. A system for injecting solid particulate catalyst particles into thereaction zone of a fluidized bed reactor for the polymerization ofgaseous monomers which comprises:

a. a reservoir for storing catalyst particles having an inlet and anoutlet,

b. catalyst feed means adapted to supply catalyst particles and an inertblanketing 'gas to the inlet of said reservoir under inert gasblanketing conditions,

c. a fluidized bed reactor having a reaction zone therein,

(1. a chambered valve exterior of said reservoir and said reactor andhaving cam timer means to provide gas tight rotation of the chamberedposition thereof to alternately face said reservoir or the reaction zoneof said fluidized bed reactor,

e. means connecting the outlet of said catalyst reservoir to the chamberof said chambered valve to provide air tight filling of said chamberwhen said chamber is positioned in fillable relation to the outlet ofsaid catalyst reservoir,

f. means to provide flow of a carrier gas through said chamber of saidchambered valve when the chamber is aligned to face said reaction zone,and

g. a conduit connecting said chambered valve and the reaction zone ofthe fluidized bed reactor, said conduit providing a gas tight zone oftravel for said catalyst particles from said chamber to said reactionzone.

2. Apparatus as claimed in claim 1 in which actuatable disruptive meansis provided in the communicating conduit to disrupt flow between saidchamber and said reaction zone.

3. Apparatus as claimed in claim 2 in which actuating means is providedto coordinate a sequence of operation of said chambered valve and saidactuatable disruptive means so as to provide sequential injection ofcatalyst particles to said reaction zone.

4. Apparatus as claimed in claim 1 in which there is provided means tosupply a continuous flow of a carrier gas through said conduit in thedirection of said reaction zone.

1. A system for injecting solid particulate catalyst particles into thereaction zone of a fluidized bed reactor for the polymerization ofgaseous monomers which comprises: a. a reservoir for storing catalystparticles having an inlet and an outlet, b. catalyst feed means adaptedto supply catalyst particles and an inert blanketing gas to the inlet ofsaid reservoir under inert gas blanketing conditions, c. a fluidized bedreactor having a reaction zone therein, d. a chambered valve exterior ofsaid reservoir and said reactor and having cam timer means to providegas tight rotation of the chambered position thereof to alternately facesaid reservoir or the reaction zone of said fluidized bed reactor, e.means connecting the outlet of said catalyst reservoir to the chamber ofsaid chambered valve to provide air tight filling of said chamber whensaid chamber is positioned in fillable relation to the outlet of saidcatalyst reservoir, f. means to provide flow of a carrier gas throughsaid chamber of said chambered valve when the chamber is aligned to facesaid reaction zone, and g. a conduit connecting said chambered valve andthe reaction zone of the fluidized bed reactor, said conduit providing agas tight zone of travel for said catalyst particles from said chamberto said reaction zone.
 2. AppAratus as claimed in claim 1 in whichactuatable disruptive means is provided in the communicating conduit todisrupt flow between said chamber and said reaction zone.
 3. Apparatusas claimed in claim 2 in which actuating means is provided to coordinatea sequence of operation of said chambered valve and said actuatabledisruptive means so as to provide sequential injection of catalystparticles to said reaction zone.
 4. Apparatus as claimed in claim 1 inwhich there is provided means to supply a continuous flow of a carriergas through said conduit in the direction of said reaction zone.